This invention relates to polymeric materials characterized by a high degree of resiliency, impact strength and corrosion resistance and well suited for use as a material of construction for chemical process equipment. The special corrosion problems encountered in the chemical process industry, the need for handling a variety of corrosive fumes, vapors, gases, and liquids, has led to the need for improved materials of construction. A variety of corrosion-resistant polymeric materials suitable for the construction of ducts, pipe, hoods, stacks, processing tanks, storage tanks, and other such chemical processing equipment, have been developed and used. Although corrosion resistance is a major consideration in the selection of such materials, other factors such as cost, availability, ease of fabrication, mechanical strength, and resistance to impact must be considered. Resins selected on the basis of corrosion resistance for the fabrication of chemical process equipment are frequently deficient in one or more of these other important factors, especially in mechanical properties such a resiliency and impact strength. The rate of failure of prior art materials through impact or vibration has been a major problem. Thus, for example, polyester resins such as those derived from bisphenol-A and fumaric acid are noted for exceptional hydrolytic and heat stability and have been used extensively in the manufacture of equipment which will withstand strong acids and bases. However, such resins, even when reinforced with glass fiber and the like are brittle and tend to fracture readily on impact or flexure. Attempts to flexibilize such materials, for example, by incorporation of polyether glycols into the resin, frequently leads to a deterioration of the corrosion resistance of the resin. Attempts to provide resins having improved impact strength has led to the development of the vinyl esters, the reaction products of diepoxides and methacrylic acid. Although these vinyl esters offer improved resilience, they still tend to crack or fracture to some degree when impacted. The cracks produced by impact often lead to a pronounced chemical attack resulting in part from a wicking action at the damaged impact site, leading to equipment failure. Other polymers have been developed wherein the introduction of urethane linkages in the polymer structure results in improvements in corrosion resistance. It is known, for example, that corrosion resistant polymers may be prepared from monomers characterized by the presence of urethane linkages and ethylenically unsaturated terminal groups. U.S. Pat. No. 3,297,745 discloses the preparation of such monomers by the reaction of one mole of a glycol such as an alkylene, arylene, or polyalkylene ether glycol, with two moles of a diisocyanate to form a diisocyanate having two urethane linkages and subsequent reaction of one mole of the diurethane diisocyanate with two moles of an ethylenically unsaturated alcohol such as an hydroxyalkylacrylate. The resultant acrylate terminated tetraurethane monomer may be polymerized or copolymerized to form corrosion-resistant polymers or copolymers. However, the polymers thus prepared, especially those prepared by curing the acrylate terminated tetraurethane monomer by copolymerization with styrene or similar vinyl monomers are rigid, brittle materials. It will be appreciated by those skilled in the art that a continuing need exists for the development corrosion-resistant materials having improved resistance to mechanical stress, shock and vibration.
Accordingly, it is an object of this invention to provide novel polymeric materials and articles manufactured therefrom having a high impact strength as well as excellent corrosion-resistant properties. It is a further object to provide a novel prepolymer composition, which may be polymerized to form a polymer suitable for the fabrication of chemical processing equipment, having a high degree of impact resistance and corrosion-resistance. Additional objects and advantages of the present invention will become apparent to those skilled in the art from the following description.